i) Field of the Invention
This invention relates to an improvement in silver staining technique for detecting one or more biocomponents fractionated on a support medium in electrophoresis or the like, such as proteins, nucleic acids, saccharides and/or lipids.
ii) Description of the Background Art
Silver staining technique is a method for detecting a substance (hereinafter called a "target substance") by treating a support medium, which contains the target substance, with a fixing agent to fix the target substance, pretreating the support medium, treating the pretreated support medium with a silver staining solution and then developing the thus-treated support medium with a reducing agent. It can analyze low-concentration samples of one or more target substances such as proteins, nucleic acids, saccharides and/or lipids, i.e., serum, urine, cerebrospinal fluid and the like without need for concentration, and is a useful analytical method employed widely in biochemical research, clinical tests, etc.
A wide variety of methods have been reported for achieving silver staining, for example, in "Seikagaku", 52, 411 (1980), "Tanpakushitsu, Kakusan, Koso", 27, 1277 (1982), "Electrophoresis", 2, 135, 141 (1981). All of these methods, however, require a long time and/or irksome procedures until completion of staining. Further, the silver-stained profiles thus obtained involve many problems such as (1) the stainability varies depending on the substance to be stained, (2) no complete staining is feasible for high-concentration samples, and (3) the contrast is low due to staining of the background. Accordingly, there has been a longstanding desire for the development of an improved silver staining technique.